Machine for manufacturing bags from preprinted webs



United States Patent lnventor Arno Finke Lengerich, Westphalia, GermanyvAppl. No. 750,389 Filed Aug. 5, 1968 Patented Nov. 3, 1970 AssigneeWindmoller & Holscher Lengerich, Westphalia, Germany Adele Finke, heirof said Arno Finke Priority Aug, 30, 1967 Germany W 44,684

MECl-IINE FOR MANUFACTURING BAGS FROM PREPRINTED WEBS 4 Claims, 5Drawing Figs.

US. Cl 93/8, 93/63 Int. CL, B31b 1/00 Field of Search 93/8, 27, 62, 63,20

[56] References Cited FOREIGN PATENTS 880,041 10/1961 Great Britain 93/8940,330 3/1956 Germany 93/8 Primary Examiner-Bernard StickneyAttarneyFleit, Gipple and Jacobson ABSTRACT: The machine comprises aperforating unit,

which precedes the tube-making unit, a tear-off unit, which succeeds thetube-making unit, a feeding unit and an end-folding and adheringmechanismyA first automatic register control system acts on theweb-feeding unitand ensures a formation of registering transverseperforation lines in the preprinted web. A second automatic registercontrol system comprises a sensing head for scanning the web providedwith transverse perforation lines, a synchronizing rotary switch, whichis in rigid operative connection with the end-folding and adheringmechanism, and a positioning device for changing the phase of theend-folding and adhering mechanism.

MACHINE FOR MANUFACTURING BAGS FROM PREPRINTEI) WEBS This inventionrelates to a machine for manufacturing bags from preprinted webs, suchas webs of paper or plastics materials, which machine comprises aperforating unit, which precedes a tube-making unit, a tear-off unit,which succeeds the tube-making unit, a feeding unit and an end-foldingand adhering mechanism.

In bag-making machines which are provided with a cutting unit instead ofperforating and tear-off units, automatic register of cut controlsystems have already been employed to ensure a register in theprocessing of preprinted webs. These known automatic register of cutcontrol systems have a photoelectric sensing head for sensing printedmarks on the web, a synchronizing rotary switch, which revolves insynchronism with the cutting mechanism, and a positioning device forcontrolling the web-feeding speed. The automatic control system acts toadjust the length of the cut sections to the spacing of the printedmarks.

if the above-mentioned bag-making machine comprising perforating andtear-off units is to be used to process preprinted webs, the knownautomatic register of cut control system will be used to drive thesynchronizing rotary switch in synchronism with the perforating unit.The web-feeding speed will then be controlled by the automatic controlsystem in such a manner that the transverse perforation lines will beformed in register with the prints on the web.

A machine which is thus equipped cannot yet make satisfactory bags/Incontrast to a bag-making machine which comprises a cutting unit, the websections which have been marked by the transverse perforation lines andare intended to form respective bags will be connected until they aresingled by being torn off. When the spacing of the transverseperforations is changed by an automatic control action, the length ofthe web portion which is provided with transverse perforation lines andextends from the perforating unit to the tear-off unit will be changedas soon as the entire length portion has been provided with perforationlines having the new spacing. If the web has six perforation line spacesbetween the perforating unit and the tear-off unit, the perforation linedisposed in the tear-off unit will be displaced by a distance which issix times the amount by which the length of the workpiece is changed.This displacement may amount to some millimeters. As a result, thetorn-off sections of the tubing are supplied in a correspondinglychanged position to the end-folding and adhering mechanism so that thereverse folding to form the bag end is not effected at the desired pointand rejects are produced.

It is an object of the invention so to develop a machine of the kindwhich has been described initially hereinbefore that satisfactory bagscan be made on it in such a manner that the reverse folding to form theends will always be effected at the correct position.

In a machine of the kind described hereinbefore, this object isaccomplished according to the invention in that a first automaticregister control system, which is known per se and acts on theweb-feeding device, is used to ensure a formation of registeringtransverse perforation lines in the preprinted web, and a secondautomatic register control system is provided, which comprises a sensinghead for sensing the web having transverse perforation lines, asynchronizing rotary switch which is in rigid operative connection withthe end-folding and adhering mechanism, and a positioning device forchanging the phase ofthe end-folding and adhering mechanism.

Whereas the essential criterion is the position of the transverseperforation lines and of the ends of the tube sections, rather than theposition of the prints, the prints or printed marks may be scannedbecause the first automatic register control system ensures that thetransverse perforation lines :have the same, predetermined distance fromthe print so that the position of the prints co-determines the positionof the tube section ends. The prints or printed marks can be sensed muchmore easily than the transverse perforation lines.

The second automatic register control system operates in such a mannerthat the synchronizing rotary switch, which is in rigid operativeconnection with the end-folding and adhering mechanism, assumes such aposition that the pulse delivered by the sensing head in response to thepassage of the printed mark is not transmitted when the end-folding andadhering mechanism is in phase with the leading edge of the workpiece,whereas the synchronizing rotary switch assumes at the time of thearrival of the pulse a position in which said pulse is transmitted tothe positioning member in one sense or the other, depending on whetherthe pulse is advanced or delayed relative to its desired-positionoccurrence, so as to change the phase of the end-folding and adheringmechanism in one sense or the other, when the end-folding and adheringmechanism is out of phase relative to the leading edge of the workpiece.Because the synchronizing rotary switch is also shifted owing to itsrigid operative connection with the endfolding and adhering mechanism,the desired value is adjusted at the same time. When the next tubesection arrives in the same position as the foregoing one, the pulsedelivered by the sensing head in response to said following workpiecewill not be transmitted by the synchronizing rotary switch to thepositioning member. This nontransmission is desired in that case.

Whereas the first automatic register control system controls the web byacting on the means which feed the web to the perforating unit, thesecond automatic register control system controls the phase relation ofthe end-folding and adhering mechanism to the web. In the first case,the positioning action on the web results in a phase shift thereofrelative to the-perforating mechanism and relative to the sensing headbut another unnecessary automatic control operation without a change ofthe desired value set at the synchronizing rotary switch is avoided. Inthe second case, the positioning action must also be applied to themeans for setting the desired value at the synchronizing rotary switch.

According to a first proposal, the positioning means for changing thephase of the end-folding and adhering mechanism and the synchronizingrotary switch may consist of an adjustable coupling, which constitutes adifferential transmission.

According to a second proposal, the means for driving the end-foldingand adhering mechanism may include a pair of helical gears, one of whichis axially slidable to effect a peripheral rotation so as to change thephase of the end-folding and adhering mechanism.

An embodiment of the invention will now be described by way of examplewith reference to the drawing, in which:

FIG. 1 is a diagrammatic side elevation showing a bag-making machineaccording to the invention.

FIG. 2 is a top plan view showing a workpiece which arrives in properposition.

FIG. 3 is a side elevation showing the workpiece according to FIG. 2when it has been folded.

FIG. 4 is a top plan view showing an arriving workpiece in an advancedposition and FIG. 5 is a side elevation showing the workpiece accordingto FIG. 4.

The feeding unit 1 continuously pulls the web 2 from the supply roll 3andover the rollers 4 to 8 and the tube-making unit 9. At a point whichis in register with the roll 5, the web is provided with a longitudinaladhesive band by means which are not shown. A first sensing head 10 isdisposed opposite to the roll 6. The roll 7 provided with a groove 11,and the roll 13, which carries a perforating knife, constitute theperforating unit I4. A first synchronizing rotary switch 15 is coaxialto the roll 13. The perforating unit produces the perforation lines 16to 21 in the web. A workpiece 22 between the pair of restraining rolls23 and the pair of tear-off rolls 24 rotating at a higher speed hasalready been separated at the perforation line 21 and has entered theend-folding and adhering mechanism 25. The perforation line 20 hasentered between the pairs of restraining and tear-off rolls 23, 24 andwill be torn immediately. A second sensing head 26 is arranged betweenthe pairs of rolls 23 and 24 and has a second synchronizing rotaryswitch 27 associated with it. The synchronizing rotary switch is inrigid operative connection with the end-folding and adhering mechanism25.

The pulses delivered by the first sensing head are transmitted by thefirst synchronizing rotary switch 15. If the printed marks 28 on thearriving web 2 are not in register with the perforating unit 14, thesepulses will result in positioning movements of a first positioningdevice 29, which is associated with the feeding unit 1 and consists,e.g., of an infinitely adjustable transmission 30 of the means fordriving the feeding unit, and an electric motor 31 for adjusting saidtransmission. The electric motor 31 is energized to rotate in onedirection or the other in response to pulses delivered by the sensinghead 10. The first automatic register control system 10,15, 29 ensuresthat the perforation lines 16 to 21 are produced in register with theprinted marks 28, which have been produced on the web together with theprints. This control is known in connection with bag-making machinesprovided with a cutting mechanism.

When the bag-making machine has been initially adjusted and started, thespacing of the prints on the web may vary,

e.g., as a result of changes in the web tension in the printing machine.In response to such change of the spacing of the prints, the firstautomatic register control system will effect a corresponding decreaseor increase of the spacing of the transverse perforation lines. When thelatter spacing is increased, e.g., the increases of all six workpiecesassociated with the perforation lines 16 to 21 will be accumulated sothat the perforation line 21 is displaced toward the end-folding andadhering mechanism by an amount which is six times the amount by whichthe spacing is changed. When the workpieces have entered the end-foldingand adhering mechanism in accordance with FIG. 2 and have been folded inaccordance with FIG. 3 along the dash-dot line 32 before the automaticcontrol operation, the workpieces will enter the end-folding andadhering mechanism in' an advanced position, as shown in FIG. 4, andwill be formed with a fold line indicated as a dash-dot line 32 in FIG.5 at a position further to the near when the automatic control operationhas been performed. This will result in a nonpermissible shortening ofthe bag, which is then provided with an excessively long, reverselyfolded end portion 33. Such bag must be rejected.

To avoid this, the second sensing head 26 is disposed adjacent to thetear-off unit 23, 24. The first automatic register control systemensures that the printed marks 28 are always at the same distance fromthe leading edges 34, 35 of the workpiece. These leading edges areoffset owing to the configuration of the transverse perforation lines inthe upper and lower plies of the workpiece. The second sensing head 26senses the position of these leading edges of the workpiece with the aidof the printed marks 28. During the initial adjustment of the bag-makingmachine, the second synchronizing rotary switch 27 was adjusted so thatthe pulses delivered by the sensing head in response to a printed mark28 on a workpiece which is positioned as shown in FIG. 2 will not betransmitted. If a subsequent automatic control operation of the firstautomatic register control system causes the workpieces to arrive at theend-folding and adhering device in a position as shown in FIG.

4, the printed mark 28 will also arrive in a changed position and thepulses delivered in response thereto will be transmitted by thesynchronizing rotary switch 27 to a positioning device 36, which adjuststhe end-folding and adhering unit 25 in such a sense that in. thecase-which is illustrated the infolding is effected at an earlier timeso that a workpiece which arrives in the position shown in FIG. 4 isinfolded as shown in FIG. 2. If the workpieces would lag behind becausethe spacing of the transverse perforation lines is reduced, the phase ofthe end-folding and adhering mechanism will be retarded accordingly.

The positioning device 36 consists of a differential transmission 37,which is included in the means for driving the endfolding and adheringmechanism and constitutes an adjustable clutch. The third member of saiddifferential transmission 37 is acted upon by a positioning motor 38 inone sense of rotation or the other in response to the position ofthesynchronizing rotary switch 27.

The adjustment of the end-folding and adhering mechanism will alsoadjust the synchronizing rotary switch 27, which is directly driven bysaid mechanism, When the adjustment has been effected, the synchronizingrotary switch is adjusted too so that a succeeding pulse, which has beenderived, e.g., from a printed mark in the position shown in FIG. 4, isno longer transmitted and further positioning movements will not beeffected until the workpieces have been shifted again.

Iclaim:

1. A machine for manufacturing bags from preprinted webs, such as websof paper or plastics materials, which machine comprises a perforatingunit, which precedes a tube-making unit, a tear-off unit, which succeedsthe tube-making unit, a feeding unit and an end-folding and adheringmechanism, characterized by a first automatic register control system,known per se, which acts on the web-feeding unit and ensures a formationof registering transverse perforation lines in the preprinted web, and asecond automatic register control system comprising a sensing head forscanning the web provided with transverse perforation lines, asynchronizing rotary switch, which is in rigid operative connection withthe endfolding and adhering mechanism,- and a positioning device forchanging the phase of the end-folding and adhering mechanism.

2. A machine according to claim 1, characterized in that the sensinghead of the second automatic register control system is disposedadjacent to the tear-off unit between a pair of restraining rolls and apair of tear-off rolls having a higher speed.

3. A machine according to claim 1, characterized in that the positioningdevice for changing the phase of the end-folding and adhering mechanismand of the synchronizing rotary switch consists of an adjustable clutchin the form of a differential transmission.

4. A machine according to claim 1, characterized in that the positioningdevice for changing the phase of the end-folding and adhering mechanismand of the synchronizing rotary switch is a pair of helical gears, whichare included in the means for driving the end-folding and adheringmechanism and comprise an axially displaceable helical gear.

